S D 



UNITED STATES DEPARTMENT OF AGRICULTURE 




,„ BULLETIN No. 1050 , 



s^^'^Ju 



Contribution from the Forest Service 
WILLIAM B. GREELEY, Forester 




SSJf'' 



Washington, D. C. 



May 12, 1922 



THE IDENTIFICATION OF TRUE MAHOGANY, 

CERTAIN SO-CALLED MAHOGANIES, AND 

SOME COMMON SUBSTITUTES. 

By Abthuk Koehlek, Specialist in Wood Structure. 



CONTENTS. 



Page 

" Mahoganies " 1 

Key for the identification of true 
mahogany and mahogany-like 

woods 2 

Description of species — 

True mahogany 4 

Crabwood 6 

Cedrela 7 

Sapeli 8 



Page. 

Description of species^ — Continued. 

" African mahogany " 9 

" Philippine mahogany '" 10 

"Colombian mahogany" 12 

" Liberville mahogany" 13 

Birch 14 

Red gum 15 

" White mahogany " 16 

(llossary 16 



"MAHOGANIES." 

Over sixty different species of timber have at one time or another 
been put on the market under the name of mahogany. Some of these 
are closely related botanically to true mahogany and others look much 
like it, while some have only the most general resemblance, and no 
relationship which imder the most liberal interpietation would en- 
title them to the name. 

The woods now most commonly sold as mahogany in this country 
are true mahogany from tropical America, "African mahogany," and 
" Philippine mahogany." The Cedrelas (Spanish cedar, etc.) are 
rarely sold as mahoganies, while crabwood, sapeli, " Colombian ma- 
hogany," and " Liberville mahogany " are imported only in small 
quantities- They are, however, described in this bulletin because of 
their resemblance to true mahogany. A description of " Avhite ma- 
hogany " is also included, for though it has no reddish-brown color 
and so is not confused with true mahogany by anyone who has seen 
a few pieces, the name might lead one unfamiliar with it to assume 
that it is true mahogany of a light color. Birch and red gum are 

79793°— 22 1 



Vy.;^;, 




RffMinirranl* 



2 BULLETIN 1050, U. S. DEPARTMENT OF AGRICULTURE. 

used principally as acknowledged imitations of mahogany, but some- 
times they are used in furniture sold as genuine mahogany. 

Of the woods mentioned in this bulletin, true mahogany, crabwood, 
the Cedrelas, sapeli, and "African maliogany " come from trees which 
are botanioally of the mahogany family (Meliacese). They are uni- 
formly distinguished from other woods herein described by the occur- 
rence of a dark reddish-brown gum in the pores. This gum does not 
completely fill the pores, but occurs as almost black masses here and 
there. It is seen best with a magnifying glass on longitudinal sur- 
faces, but in many specimens is visible without a lens. Of course, 
woods of other families may have dark gum in the pores, but none 
such are commonly substituted for mahogany.^ 

Key fob the Identification of Teue Mahogany and Mahoganylike Woods.* 

(Also read carefully the descriptions of these species in the following pages 
and study the illustrations.) 

I. Wood light to dark reddish brown. 

A. Many pores contain more or less of a very dark reddish brown 
gum visible on longitudinal and end surfaces. Otherwise the 
pores are open, no tyloses being present. The gum is visible 
without, but better with a hand lens. 

1. Growth rings sharply but not always conspicuously defined. 
AA. Wood without characteristic odor. Growth rings de- 
fined by distinct but not always conspicuous lines of 
soft tissue 3^ to V2 inch apart. Pores in each growth 
ring almost uniform in size. 

a. Lines of soft tissue light-colored and conspicuous. 

Rays on a freshly cut or split radial surface not 
much darker than adjacent fibers. Tangential sur- 
face occasionally but not always figured with very 
fine bands which run across the grain, due to the 
rays being in stories. Wood highly variable in 
weight and light to dark reddish brown in color. 
True mahogany (Stmetenia spp.). 

b. Lines of soft tissue mostly dark, not conspicuous. 

Rays on a freshly cut or split radial surface consid- 
erably darker and more reddish than adjacent 
fibers and usually with a slight purplish tinge. 
Rays not in stories. Wood moderately hard. Color 
more of a plain brown than in true mahogany. 
Crabwood (Carapa guianensis). 

1 To one familiar with the examination of wood sections under a high-power microscope, 
the exceedingly fine pits (as small as in birch) between adjacent vessels and also the 
septate wood fibers found in Swietenia, Carapa, Entandrophragma, and Kliaya offer an 
additional means of distinguishing these members of the mahogany family from others 
not of the same family. In Cedrela the pits are larger, but also very numerous, and the 
wood fibei-s are sparingly septate. Boswellia (family Burseraceaj) also has septate wood 
fibers, but the pits in the vessel walls are comparatively large. 

2 Unless otherwise directed all observations as to structure should be made on the end 
surface cut smoothly with a very sharp knife, and all observations as to color should 
be made on freshly cut longitudinal surfaces of the heartwood. 



LIBRARY OF CONGRESS 
DOQUMCNT« OiViSION 



SBs^ 



IDENTIFICATION OF TEUE MAHOGANY. 6 

I. Wood light to dark reddish brown — Continued. 

A. Many pores contain, etc. — Continued. 

1. Growth rings, etc. — Continued. 
BB. Wood with characteristic odor of cigar-box cedar. 

rf Growth rings defined by distinct lighter-colored lines 
. . ' and usually, but not always, by rows of larger pores, 
riZ) ff ' approaching ring-porous structure as in ash, oak, hick- 
ory, and some other hardwoods. Wood light and soft. 

Spanish cedar {Cedrela odorata). 

Brazilian cedar {Cedrela brasiliensis). 

Toon (Cedrela toona). 

(Odor most pronounced in Spanish cedar.) 

2. Growth rings not clearly defined by lighter colored lines or 

otherwise. 

AA. Numerous tangential lines of soft tissue either lighter 
or darker colored than the adjacent fibers and readily 
visible without a lens — 40 to 50 per inch of radius. 
Rays usually not in stories and white substance not 
found in pores. Wood moderately heavy. 
Sapeli (Entandrophragma candollei). 

BB. Tangential lines of soft tissue either not present or 
very rarely an occasional one ; however, darker or 
lighter colored zones without definite boundary, as 
seen under a hand lens, may be present. Color same 
as true mahogany, or quite often with a slight pur- 
plish tinge when freshly cut. Rays not in stories, or 
only locally, and white substance not found in pores 
as in some true mahogany. Wood moderately heavy. 
"African mahogany " (Khaya spp.). 

B. Pores do not contain a reddish gum. 

1. Pores readily visible without a lens on smoothly cut surfaces. 
AA. Occasional short or long white tangential lines present, 
from Vs inch to several inches apart radially, visible 
without a lens. When viewe«l with a magnifying 
glass these lines appear to be made up of a row of 
small ducts, much smaller than the pores, and com- 
pletely filled with a wh'ite substance. Considerable 
variation in color. Weight variable, about the same 
as mahogany. 

" Philippine mahogany " (SJiorea spp.). 

a. Color moderately light to dark reddish brown, with 
purplish tinge. Pores comparatively small but vis- 
ible without a lens. Pinworm holes rare. 

Tanguile (Shorca polysperma). 

6. Color dark reddish brown without purplish tinge. 
Pores slightly larger than in tanguile. Pinworm 
holes common. 

Red lauaan (Shorea negrosensis) . 

c. Color very pale reddish brown without purplish tinge. 
Pores slightly larger than in tanguile. Pinworm 
holes rare.* 
Almon (Shorea eximia). 

" On account of variations in the structure and color of tanguile, red lauaan, and almon, 
it is not always possible to distinguish the wood of these species by means of the char- 
acteristics given in this key, which is based on typical features. 



4 BULLETIN^ 1050, U. S. DEPARTMENT OF AGRICULTURE. 

I. Wood light to dark reddish brown— Continued. 

B. Pores do not contain a reddish gum— Continued. 

1. Pores readily visible, etc.— Continued. 

BB. No white tangential lines consisting of rows of ducts, 
but numerous very fine continuous lighter-colored lines 
of soft tissue present, 120 to 175 per inch of radius, 
barely visible without a magnifying glass. Wood 
moderately hea\T^. 
" Colombian mahogany " {Cariniana pyrifonnis). 

CC. No fine light-colored tangential lines present; struc- 
ture very homogeneous. Color light purplish brown. 
Wood moderately light and soft. 
" Liberville mahogany " (BoswcUia Jdaincana). 

2. Pores not readily visible without a lens. 

AA. Pores barely visible without a lens on smoothly cut sur- 
faces in good light ; very distinct under a lens. The 
heartwood is dull reddish brown ; the wide sapwood is 
white. The wood Is heavy, usually straight-grained. 

Sweet birch (Betula Imta). 

Yellow birch {Betula lutea). 

BB. Pores not visible without a lens; very small and uni- 
formly distributed as seen with a lens. The heart- 
wood is reddish brown, often with darker streaks; 
the wide sapwood is pinkish white (unless blued by 
stain). The wood is moderately heavy and usually 
has interlocked grain. 

^^^ ^'"™ {Liquidambar styraciflua). 

II. Wood without reddish tinge. Color creamy white to yellowish brown. 
Growth rings sharply but not conspicuously defined by white tan- 
gential lines or by a slightly darker band of sununonvood. Pores 
of practically uniform size thn.ughout growtli ring, barely visible 
on a smoothly nit end surface, but very distinct as fine grooves on 
planed longitudinal surfaces: mostly filled witii tyloses. Wood 
with interlocked grain and moderately heavy. 
"White mahogany." or primavera {Tabcbuia doniirii-sitnthii) 

h/.*?«f57'^^'' '?'''''.?^.'',f ".'■'^^ ^^ ^"''^"t ^^^^^^^ «°&e. and when taken bv itself might 
he classified under " II " ahove. although fresh ent.. are almost white For means of 
distingruishing birch from primavera, see descriptions of these species. 

DESCRIPTION OF SPECIES. 

TRUE MAHOGANY.' 

f^ioietenia mahagoni Jacq.»; Swictcnia macTophylla King.; Sioictenia Hrrhafa 

Blake; Swietenia humilis Zucco. ; Swietenia candoUci Pittier. 

Mahogaxy Family (MELiACE.ii:). 

OTHER NAMES. 

True mahogany comprises all the species of the l>otanical -enus 
*^^czetema, ot which five are known at present." 

*See TT. S. Dept. Asr. Rnlletin 474. "True Mahosany," by C D Mell For sale hv 
Snpenntendent of Documents. Government Printing Offlce/washTngfon D.C Priced 

wh7«rsrdTscr£d ^TTp^^^""^"'^ ^^ "^"'^"■^ ^° «''''-^«"- «^ *'- — of the person 
c^^T^dL^s, ;'r7o;"ppr yjllojr^f ^J!^-"'-- •^°--' -^ «- Wash..gton Acad. 



IDENTIFICATION OF TRUE MAHOGANY. 5 

Mahogany is rarely sold under any other trade name, except that 
the very light grades are called "bay mahogany" or "bay wood." 
The Spanish name is "caoba" and in Florida it is called "maderia." 
Stuletenla cii'rhata is known locally as " venadillo." 

Occasionally the name mahogany is modified so as to indicate the 
country it came from, as Honduras mahogany. Tabasco mahogany, 
Cuban mahogany, etc. 

WHERE GROWN. 

True mahogany grows in tropical America from southern Florida 
and northern Mexico to northern South America, including the West 
Indies. It does not grow naturally in Brazil or other parts of the 
world. xVccording to Blake," Swietenia- mahagonl grows in the 
West Indies, Bermuda, and the keys of southern Florida ; S. macro- 
phylla grows along the eastern coast from the State of Tabasco, 
Mexico, to Honduras and possibly farther south; S. hv/milis is a 
native tree of the west coast from Guerrero, Mexico, to northwestern 
Guatemala; S. dn^hata is known to occur naturally in western 
Mexico from Sinaloa to El Salvador; and S. candollei is a native of 
Venezuela. Of ih^ five species, Swietenia mahagoni and S. vuicro- 
fKylla are the more common. Sivietenia macro'p7i7jlla-^ which has 
larger leaves and larger fruit than the West Indian species, grows 
principally on low lands, and, as a rule, produces softer and lighter 
colored wood than S. mahagoni; however, no distinct differences in 
the wood by means of which each, species can be identified have so 
far been obsei'^'ed. 

PHYSICAL PROPERTIES. 

The M'ood of true mahogany is highly variable in weight; pieces 
ranging in specific gravity from 0.34 to 0.90, based on oven-dry 
weight and oven-dry volume, have been found, although very few 
pieces have a specific gravity greater than 0.70. The wood from 
southern Florida and Cuba averages heavier than that from Central 
America. 

The color of true mahogany varies from very pale to very dark 
reddish-brown. The wood is without characteristic odor or taste. 
True mahogany usually has interlocked grain, which gives the 
" ribbon " effect to quarter-sawed material. Unlike most other Avoods 
with interlocked grain, it does not warp easil3^ 

STRUCTUEE, 

The pores in true mahogany are plainly visible without a hand 
lens as minute holes on a smoothly cut end surface (see fig. 1) and 
as grooves on longitudinal surfaces. They are scattered singly or in 
short radial rows of 2 to 4. Some of the pores are filled with a dark 

" Blake, S. P., "Revision of the True Mahoganies." Journal of the Washington Acad- 
emy of Sciences, vol. 10, pp. 286-297. f. 1-2. 



6 BULLETIN 1050, U. S. DEPARTMENT OF AGEICULTURE. 

brown gum, but less plentifully in the light-colored, soft grades than 
in the darker grades. In heavy grades some pores also contain a 
whitish substance. (See fig. 1.^) These pores differ from the white 
gum ducts in " Philippine mahogany " in being scattered singly in- 
stead of in tangential rows ; furthermore, the gum ducts in " Philip- 
pine mahogany " are smaller than the sap pores. 

The rays on the radial surface are very distinct. On account of 
the luster of both rays and wood fibers, the rays may appear lighter 
or darker than the surrounding areas, depending on how the light is 
reflected. Actually the rays are only slightly, if any, darker than 
the surrounding fibers, a characteristic which helps to distinguish 
mahogany from crabwood, in which the rays are considerably darker. 
In some pieces of mahogany the rays are in rows or stories extending 
at right angles to the grain — that is, horizontally in the tree — show- 
ing up on the tangential surface as striations, or " ripple " marks, 
across the grain. (See fig. 12.) This condition of the rays being in 
stories is not always found in true mahogany, but is rarely found in 
any of the other species herein described, although it is common in a 
number of other woods not mentioned in tliis publication. 

The growth rings in true mahogany are defined by light-colored 
concentric lines, in some pieces very close together and in others 
one half inch or more apart, with considerable variation in the same 
piece. 

CRABWOOD. 

{Carapo (juiuncnsis Aubl.) 

Mahogany Family (Meliacile). 

other names. 

This wood is known as " Para mahogany," " Brazilian mahogany," 
" Demerara mahogany," " British Guiana mahogany," and in South 
America as " andiroba." 

WHERE GROWN. 

Crabwood grows in northern South America as far south as the 
Amazon Valley, although the exact limits of its geographical dis- 
tribution are not known. It is a common timber tree of British 
Guiana. 

PHYSICAL PROPERTIES. 

The wood is moderately heavy and hard, and similar to magohany, 
except that such extremes of very light and very heavy grades are not 
found. 

The color is similar to that of true mahogany, except that it is not 
quite so reddish, but rather more of a plain brown. 

' The text figures will be found grouped at the end of this bulletin. 



IDENTIFICATION OF TRUE MAHOGANY. 7 

The grain is straighter than in mahogany, but the wood is said to 
check and warp more easily in seasoning ; however, the Forest Service 
has no authentic information on its seasoning qualities. 

STRUCTUBE. 

The pores are plainly visible on smoothly cut transverse and lon- 
gitudinal surfaces. They are fairly uniform in size and evenly dis- 
tributed, and in all respects closely similar to those of true mahogany, 
but somewhat smaller than in "African mahogany." Hardened 
masses of dark-brown gum are visible here and there in the pores. 
These can best be seen with a hand lens on longitudinal surfaces. No 
whitish deposits in the pores of this wood have been noticed by the 
author, although Dixon ® reports their occurrence. (See fig. 2.) 

The rays are very fine on cross-section, but quite conspicuous on 
radial surfaces, owing to the fact that they contain reddish coloring 
matter. (See fig. 13.) This reddish color of the rays is one of the 
chief means of distinguishing crabwood from true mahogany, 
although the rays in mahogany may appear darker if the light is re- 
flected in a certain manner. All " Philippine mahogany " and occa- 
sional pieces of "African mahogany " may also have reddish rays, but 
can be distinguished from crabwood by other means. (See key.) 

The growth rings, which are very irregular in width, are faintly 
defined by somewhat lighter colored lines of soft tissue similar to 
but much less conspicuous than those in mahogany. 

CEDRELA. 

Spanish Cedar (Cedrela odorata L.) ; Brazilian Cedar (Cedrela hrasiliensis 
Juss.) ; Toon (Cedrela toona Roxb. or Toona dliata Roeni. or Toona toona- 
Wight). 

Mahogany Family (Meliacele). 
other names. 

Spanish cedar ^ is also commonly known as " cigar-box cedar." 
Brazilian cedar ^ is known in South America as " cedro." 
Toon has been marketed as " Indian mahogany " and " toona ma- 
hogany." 

The Spanish and Brazilian cedars are rarely sold as mahogany, 
but because of their resemblance to the light grades of true ma- 
hogany their description is included here. 

* Dixon, H. H., " Mahogany, and the Recognition of Some of the Different Kinds by 
Their Microscopic Characteristics." Scientific Proceedings of the Royal Dublin Society, 
Vol. XV (^f. S.), No. 34, Dec, 1918. 

8 These species are not true cedars. Tliey belong to the hardwood class, that is, trees 
with broad leaves, bit were probably given the name of cedar because of the aromatic 
odor of the wood. 



8 BULLETIN 1050, U. S. DEPARTMENT OF AGRICULTURE. 

WHEKK GROWN. 

The true Spanish cedar {Cedrela odorata L.) is not definitely 
known outside of the West Indies and French Guiana. 

Brazilian cedar grows in Brazil and northern Argentina. X num- 
ber of minor species of Cedrela are also found in Mexico, Central 
America, and South America. 

Toon is a native of India, Java, and Australia, and is shipped to 
the United States in comparatively small quantities. A similar 
species, calantas {Toana calantas Merr. and Rolfe), is of com- 
mercial importance in the Philippine Islands. 

PHYSICAL PROPERTIES. 

The color of these woods is very much like that of true mahogany. 
In weight they are lighter than the average mahogany. They have 
a distinct, pleasant odor, most pronounced in Spanish cedar. The 
grain of the wood is not interlocked so much as in mahogany. 

STRUCTURE. 

The pores of the Cedrelas are plainly visible with the unaided eye. 
(See fig. 3.) Some of the pores are partly filled with a dark reddish- 
brown gum, a characteristic of the mahogany family. As a rule, but 
not always, the pores are slightly larger at the beginning of each 
growth ring, making the wo6d " ring-porous." The growth rings are 
also defined by a light-colored line of soft tissue, as in true mahogany. 
This line is not so conspicuous in toon as in the two species from the 
American Tropics. 

The rays are very fine, being barely visible with the unaided eye 
on a smoothly cut end surface. On radial surfaces they are very 
lustrous and appear lighter or darker than the surrounding fibers, 
depending on how they reflect the light. These rays are never 
storied, as in some pieces of mahogany. 

SAPELI.io 

Entandrophragma candollei Harms. 
Mahogany Family (Meliace^). 

other name. 

"African mahogany." 

Other species of Entandrophragma, with similar characteristics, 
may also be included with sapeli. Entandrophragma candollei is 
known as " unscented mahogany," and E. utilis as "scented 
mahogany." ^^ 



'" Also spelled " sapele ;" in either case pronounced sap'-el-e. 

" Unwin, A. Harold, " West African Forests and Forestry." T. Fisher Unwin. pub- 
lisher, London, 1920. 



IDENTIFICATION OF TRUE MAHOGANY. 9 

WHERE GROWN. 

Countries bordering on the Gulf of Guinea, west coast of Africa. 

PHYSICAL PROPERTIES. 

The wood is considerably heavier than that of the Khayas. The 
grain may be very much interlocked, but no information as to whether 
the wood warps easily is available. No pronounced odor or taste is 
present in the wood, although a slight odor, faintly resembling that 
of Spanish cedar, is noticeable in some pieces. 

STRUCTURE. 

The pores are visible without magnification on smoothly cut end 
and longitudinal surfaces. They are fairly uniform in size, evenly 
distributed, singly or often in twos, and occasionally in threes. As 
in other species of the mahogany family, the pores contain morei or 
less of a dark reddish-brown gum. 

The chief characteristic of sapeli is the presence of numerous tan- 
gential lines of soft tissue seen on a smoothly cut end section of the 
wood. (See fig. 4.) These lines are usually darker, but may be 
lighter, than the other portion of the wood and average 40 to 50 to 
the radial inch. The constant closeness of these lines eliminates the 
possibility of mistaking them for lines limiting growth rings, as in 
true mahogany. Seasonal growth rings are not clearly defined. 
According to Kecord,^^ the rays are more or less storied as seen on 
the tangential faces, but this was not the case in the specimens 
available to the writer. 

"AFRICAN MAHOGANY." 

(Khaya spp.) 

Mahogany Family (Meliace^). 

other names. 

Several species of the genus Khaya are marketed as African 
mahogany.^^ Probably the most common one is Khaya senegalensw 
A. Juss. Other names applied to these species are " Senegal mahog- 
any," " Gambia mahogany," " Benin mahogany," and " Gaboon ma- 
hogany," indicating the regions from which the species are obtained. 

Other species, as sapeli, and some not of the mahogany family, 
are occasionally called "African mahogany," but very little wood 
of these species is brought into the United States. 

'2 Record, S. J., " Mahogany and Some of Its Substitutes." Journal of Forestry, Vol. 
XVII, No. 1, Jan., 1919. 

13 For detailed information concerning the various species of Khaya see Unwin, Har- 
old A., " West African Forests and Forestry." 



10 BULLETIN 1050, U. S. DEPAETMENT OF AGRICULTURE. 

WHERE GROWN. 

West coast of Africa and inland along a belt from 15° north to 
20° south of the Equator, and found occasionally in Uganda and 
Mozambique on the east coast. 

PHYSICAL PROPERTIES. 

African mahogany is similar to true mahogany in its properties, 
except that it does not show such extremes of density and color. 
Occasional boards have a purplish tinge mixed with the usual red- 
dish-brown color. 

Interlocked grain is usually present, but, as in true mahogany, is 
not associated with excessive warping. 

STRUCTURE. 

The pores are plainly visible without a lens; in fact, they are 
slightly larger than in true mahogany, giving the wood a coarser 
texture. They are fairly uniform in size and evenly distributed. 
(See fig. 5.) Abundant dark reddish-brown gum is found in most 
of the pores. 

No distinct growth rings are present. Lighter and darker con- 
centric zones are often found, but without a sharp line of demarca- 
tion. The absence of the fine tangential lines limiting growth 
rings in true mahogany of tropical America is the chief feature of 
distinction between these two woods. The author has noticed one 
or two such lines in certain pieces of "African mahogany," but not 
many, as is usual in true mahogany. Care must be taken not to 
mistake knife marks for such fine lines. 

The rays are barely visible without a lens on a smoothly cut end 
surface, but are very plain and lustrous on radial surfaces. They 
are never conspicuously storied on the tangential faces, as in true 
mahogany, although they may be in irregular stories locally. 

" PHILIPPINE MAHOGANY." '* 

Tangiiile" (Sharea polysperma Merr.) ; Red laiiaan " (SJiorea negrosensis 
Foxw.) ; Almon (Shorea eximia Scheff.). 

Lauaan or Dipterocarp Family (Dipterocarpace^). 

OTHER names. 

Tanguile is also known as " Bataan mahogany " and " tanguile ma- 
hogany.'' The heavier grades of red lauaan are substituted for tan- 

" See Philippine Bureau of Forestry Bulletin 14, " Commercial Woods of the Philip- 
pines : Their Preparation and Uses," by E. E. Schneider. Bureau of Printing. Manila, 
P. I. Price, $1. 

15 Also spelled " tangil." Pronounced tang-he'-le. 

i« Pronounced lau-ah-an'. 






IDENTIFICATION OF TKUE MAHOGANY. H 

guile on the Manila market. Almon has no other common names 
except in the native dialect. 

Tanguile and red lauaan constitute the bulk of so-called " Philip- 
pine mahogany " sent to the United States. Almon is included occa- 
sionally. Rarely, other species of the Dipterocarp family may be 
included, especially white lauaan {Pentacme contorta Merr. and 
Rolfe) and bagtican {Parashorea m^ilaanonan (Blanco) Merr.). 
When tanguile is desired, genuine tanguile should be specified. 

WHEKE GROWN. 

Philippine Islands. 

PHYSICAL PEOPERTIES. 

Tanguile is " soft to moderately hard ; light to moderately heavy, 
specific gravity 0.469 to 0.509 (Gardner) ; ^^ heartwood pale red to 
dark reddish-brown; grain distinctly crossed, producing a broad, 
conspicuous ribbon when quarter-sawed ; seasons well, but may warp 
if not carefully stacked ; easy to work." ^^ 

Red lauaan is " soft to moderately hard ; light to moderately heavy, 
specific gravity 0.406 (Gardner) ; heartwood light red to dark red- 
dish brown; grain distinctly crossed, forming a conspicuous ribbon 
when quarter-sawed; texture rather coarse; seasons well, splitting 
and warping very little ; easy to work." ^^ 

Almon is "soft; light, specific gravity 4.464 (Gardner); heart- 
wood very pale red ; texture rather coarse ; grain somewhat crossed, 
making a narrow,distinct ribbon when quarter-sawed, small but dis- 
tinct silver grain; seasons well, checking and warping very little; 
very easy to work." ^^ 

Tanguile, in general, is slightly heavier, harder, stronger, and finer- 
grained than either red lauaan or almon. 

STRUCTXJKE. 

The pores are very distinct on smoothly cut transverse and longi- 
tudinal surfaces. They are fairly uniform in size in each species, but 
average slightly smaller in tanguile than in red lauaan and almon. 
They are evenly distributed, singly or occasionally by twos. The 
pores are open for the most part, but occasionally contain tyloses. 
Reddish-brown gum is never found in the pores. 

White tangential lines varying in length from very short to the 
full thickness of a board are usually common on the cross-section (see 

1'' The moisture percentage and the volume (oven-dry or otherwise) on which this 
specific gravity is based are not given, but undoubtedly the basis of computation was the 
same as that used in computing the specific gravities of red lauaan and almon quoted in 
the succeeding paragraphs. Forest Products Laboratory determinations show an average 
specific gravity for tanguile based on the oven-dry weight and oven-dry volume of 0.57. 

^"Philippine Bureau of Forestry Bulletin 14, pp. 168-171. 



12 BULLETIN 1050, U. S. DEPARTMENT OF AGRICULTURE. 

fig. 6), but may be absent for areas of several square inches. Under 
a magnifying glass it can be seen that these white lines are made up 
of rows of ducts (smaller than the pores) containing a white gum, 
differing in this respect and in not being continuous from the light- 
colored lines found in true mahogany. These tangential rows of 
white gum ducts are found in no other species sold as mahogany, 
unless it be in other species of the Dipterocarp family which may 
occasionally be included in shipments of " Philippine mahogany." 

Short lines of lighter colored tissue extending for a short dis- 
tance tangentially from the pores may occasionally be seen with a 
lens on smoothly cut end surfaces. It is not necessary to look for 
these, however, in distinguishing " Philippine mahogany " from other 
species herein described. 

The rays are not visible without lens on an end section, but are very 
conspicuous on radial surfaces because of their reddish color. 

No well-defined growth rings are present, although the rows of 
gum ducts when long might be mistaken for the termination of 
seasonal layers. 

" COLOMBIAN MAHOGANY." "> 

(Canniana pyriformis Miers.) 
Monkey-pod Family (Lecythidace^.) 
other names. 
Cariniana, albarco (Colombia). 

WHERE GROWN. 

Colombia, South America. 

PHYSICAL PROPERTIES. 

The wood has about the same weight and color as moderately heavy 
mahogany, except that a slight purplish tinge is usually present. 
It has more or less interlocked grain, but is said not to give any 
trouble by warping when properly seasoned. 

STRUCTURE. 

The pores are visible without a lens on smoothly cut end and 
longitudinal surfaces. They are fairly uniform in size, and evenly 
scattered, singly or occasionally by twos. They do not contain 
brownish gum, as do those in true mahogany, but contain some 
tyloses. The growth rings are very faintly defined by a slight 
difference in the size of the pores. 

2« See Forest Service Circular 185, " Colombian Mahogany," by Geo. B. Sudworth and 
C. D. Mell. Government Printing Office, Washington, D. C. Price, o cents. 



IDENTIFICATION OF TEUE MAHOGANY. 13 

A striking characteristic of the wood is the presence of very numer- 
ous, fine, lighter colored, tangential lines of soft tissue, barely visible 
without a lens. These lines are fairly evenly spaced and average 
from 120 to 175 per inch of radius. (See fig. 7.) Similar lines, but 
wider apart, are found in sapeli, and the presence in " Colombian 
mahogany " of tyloses instead of gum is an additional aid in distin- 
guishing the two species. 

The rays are not distinctly visible on cross sections, but on radial 
surfaces are very distinct because of their reddish-brown color. 

" LIBERVILLE MAHOGANY." 

(Bosicellia klwincana Pierre.) 
Myrkh Family ( Bukseeace^ ) . 
other names. 
Gaboon mahogany ; okume ; okoumie ; African cedar. 

WHERE GROWN. - 

French Kongo and adjacent territory of Africa. 

PHYSICAL PROPERTIES. 

The wood is lighter and softer than the average genuine mahogany, 
although it is firm enough to be used for furniture and similar arti- 
cles. It is pale pinkish-brown or pale flesh-colored with a faint 
lavender tinge. Dressed surfaces appear lustrous. The wood is 
without characteristic odor or taste. 

The grain runs straighter than in mahogany, and hence the "rib- 
bon " effect is not so pronounced in quarter-sawed lumber. 

STRUCTURE. 

The pores are very distinct to the unaided eye, being of about the 
same size as those in true mahogany. They are scattered singly, or 
occasionally several in short radial rows. The pores are empty, 
except for occasional tyloses. 

Tangential lines of light-colored tissue are absent, although poorly 
defined tangential zones of darker and lighter wood may occasion- 
ally be present. (See fig. 8.) 

The rays are very fine, not visible on a cross-section without a 
hand lens.-^ On radial surfaces they are distinct but comparatively 
small, and not much darker than the surrounding wood. 

21 " Liberville mahogany " and " Colombian mahogany " are the only species herein 
described in which the rays are characteristically 2 (occasionally 1 or 3) cells wide, as 
seen with a high-power microscope on the tangential section. In all the other species 
the larger rays are 4 or more colls wide, except in some pieces of red gum in which the 
rays are mostly 2 or 3 cells wide. 



14 BULLETIN 1050, U. S. DEPAETMENT OF AGRICULTURE. 

BIRCH. 

Sweet birch (Bettila lenta Linn.) ; yellow birch (Betula hitea Michx. f.). 
BiKCH Family (Betulace^). 

OTHER NAMES. 

Sweet birch is also known as cherry birch, black birch, and ma- 
hogany birch. 

Yellow birch is also known as gray birch, silver birch, and swamp 
birch. 

The heartwood of both species is usually sold as " red birch " and 
the sap wood as " yellow birch." 

Other species of birch are rarely cut into lumber. 

WHERE GROWN. 

Sweet birch grows within an area that extends from Newfoundland 
to eastern Iowa, and south to northern Florida. It is of commer- 
cial importance, principally in the East, from New York State south 
along the Appalachian Mountains, although it is cut as far west as 
Wisconsin. 

Yellow birch occurs from -Newfoundland to northern Minnesota, 
and through the northern States to eastern Tennessee, North Caro- 
lina, and Delaware. It is most abundant and reaches its largest size 
in northern New England and New York and in northern Michigan 
and Wisconsin. 

PHYSICAL PROPERTIES. 

Although sweet birch averages slightly heavier and harder than 
yellow birch, the difference is so little that usually no distinction is 
made between the two species when used in the form of lumber. 
Both species are hard, heavy, and strong in bending. 

Birch has somewhat of a tendency to warp, but not so much as 
red gum and other species with decidedly interlocked grain. 

The heartwood is reddish brown; the sapwood, which is often 
wide, is practically white. Much sapwood is used in the manufac- 
ture of furniture with a mahogany finish. It is difficult to hide its 
identity since any wear or fracture is likely to disclose the white 
wood underneath the finish. 

STRUCTURE. 

The pores in birch are of such size that they can barely be seen 
in good light without a lens on the smoothly cut end surface. On 
the longitudinal dressed surface they appear as very fine grooves. 
They are almjost uniform in size throughout each annual ring, 
although occasionally they are noticeably smaller toward the end of 
each year's growth. (See fig. 9.) The annual rings are defined by 
fine lines. 



IDENTIFICATION OF TRUE MAHOGANY. 15 

The rays are not distinctly visible without a lens on the cross- 
section. On radial surfaces they appear as fine reddish-brown 
"flakes." 

RED GUM. 

(Liquidambar styraciflna Linn.) 

Witch Hazel Family (Hamamelidace^e). 

other names. 

Sweet gum; star-leaved gum; hazel wood; satin walnut (Europe) ; 
sap gum (sapwood only). 

WHERE GROWN. 

In the United States south of a line from Connecticut through 
southern Illinois and Eastern Texas, except in southern Florida. 
It is very uncommon in the Southern Appalachian Mountains and 
the surrounding highlands, but is found on the mountains of Central 
and Southern Mexico and on the highlands of Guatemala. Most 
abundant commercially in the bottom lands of the lower Mississippi 
Valley. 

PHYSICAL PROPERTIES. 

The wood is moderately heavy and moderately hard. It usually 
has interlocked grain, which causes it to warp, especially when plain 
sawed, unless properly seasoned. 

The heartwood is reddish-brown, varying more or less in shade. 
It often contains darker streaks which add to its beauty. The sap- 
wood is pinkish white unless blued by stain. It is often wide and is 
sold separately as " sap gum." 

STRUCTURE. 

The pores are so small that they can not be seen without a good 
magnifying glass. (See fig. 10.) This feature distinguishes red 
gum from mahogany and mahogany-like woods. The pores are of 
uniform size and distribution throughout each annual ring, making 
it difficult to differentiate each year's growth, although on careful 
examination with a lens a fine line can be seen separating the annual 
growth layers. 

The rays are fairly distinct, but not at all conspicuous without a 
lens on either an end or a radial surface, since they are relatively 
small and of about the same color as the surrounding wood. 

Since the annual rings, pores, or rays do not stand out clearly, red 
gum has no characteristic figure except for the darker streaks in 
some grades. 



16 BULLETIN 1050, U. S. DEPARTMENT OF AGRICULTURE. 

"WHITE MAHOGANY." 

{Tabebnia donnell-smithii Rose.) 

Trumpet-Creeper or Catalpa Family (Bignoniace^). 

other names. 

Prima vera. The names " jenicero " or " genesero " have also been 
applied to this wood, but these names are also used for an entirely 
different Mexican species, namely, guanacaste (Enterolohmm 
cyclocarpu77i) . 

WHERE grown. 

Western coast of Mexico and southward to Guatemala. 

PHYSICAL PROPERTIES. 

The wood is moderately heavy and hard, works well, and is said 
to give little trouble by warping. It is creamy white to yellowish- 
brown in color. The grain is interlocked, and the pores are of about 
the same size as in true mahogany, so that the figure produced, espe- 
cially when finished with a mahogany stain, is similar to that of true 
mahogany. 

STRUCTURE. 

The pores are plainly visible on longitudinal surfaces as grooves, 
and can be seen on smoothly cut end surfaces as minute openings. 
They are arranged so as to form diagonal or wavy tangential rows, 
especially in the outer portion of each growth ring as seen on the 
cross-section. (See fig. 11.) Tyloses are very common in the pores. 
Fine tangential lines, often accompanied by a darker layer of sum- 
merwood, mark the limits of the growth rings. In some pieces the 
pores are also slightly larger at the beginning of each growth ring, 
making the rings more conspicuous. 

The rays are barely visible on cross-section and inconspicuous on 
radial surfaces. On tangential faces they may or may not appear 
storied. When storied they never produce conspicuous " ripple " 
marks, as in true mahogany. 

GLOSSARY. 

Density. — Amount of wood substance, equivalent to oven-dry 
weight. 

Ducts^ or gum ducts. — Special ducts for storing or conveying gum. 
Found only in a few species of hardwoods; usually smaller and less 
numerous than the pores for conducting sap. 

Faimly. — Botanically speaking^ a group of plants having certain 
fundamental resemblances, especially in the flowers and fruit, yet 
differing more or less in this and other respects. For example, 



IDENTIFICATIOlSr OF TEUE MAHOGANY. 17 

apple, pear, and quince belong to one family, and walnut and hick- 
ory to another family. 

Fibers. — The comparatively long thin cells usually comprising the 
bulk of the wood, but too small to be seen except with a high-powered 
microscope. Distinguished from the pores in the hardwoods, which 
are larger but less numerous. 

Growth rings. — The well-defined layers of wood put on each season 
usually, but not necessarily, limited to one each year. 

Gum. — A white or dark deposit, partly or wholly filling the sap 
pores or the gum ducts of certain wood's. 

Interlocked grain. — Fibers slanting around the tree in one direction 
for a number of years and then reversing to the other direction, and 
later reversing again, and so on, producing a " ribbon " effect on 
quarter-sawed lumber. 

Light-colored lines. — Very thin light-colored lines extending cir- 
cumferentially on the cross-section. These may mark the end of 
each growth ring, or many may be formed each season, as in sapeli 
and " Colombian mahogany." Composed of soft tissue technically 
known as parenchyma. 

Longitudinal surfaces. — Either radial or tangential surfaces, as 
distinguished from cross-section, or end grain. 

Pores. — Larger cells with open ends set one above the other, and 
used for conducting sap, as distinguished from the smaller wood 
fibers with closed ends used to give strength to the tree trunk. (True 
pores are not found in the coniferous woods, in which the fibers serve 
the combined purpose of conducting sap and giving strength to the 
tree. ) 

Radial. — Along the radius. 

Radicd surface. — A longitudinal surface cut approximately along 
the radius of the log, that is, from the bark toward the center ; equiv- 
alent of edge grain or quarter-sawed surface. 

Rays. — Rows of cells extending horizontally in a tree from the 
bank inwardly at right angles to the grain. Visible on strictly 
radial surfaces of all woods; very conspicuous in quartered oak. 
(See fig. 13.) On end surfaces they may be seen with a lens, or 
occasionally without, as fine radial lines crossing the growth 'rings. 

Ring-yorous. — Having the pores at the beginning of each growth 
ring comparatively large, with more or less abrupt decrease in size 
toward the outer portion of the growth ring. 

Riffle marks. — Fine transverse markings uniformly spaced on 
the tangential faces of wood. (See fig. 12.) 

Soft tissue. — Thin-walled cells, often in rows, usually producing 
lighter-colored lines when cut across the grain, used to store food. 
Technically called parenchyma. 
79793°— 22 2 



18 BULLETIN 1050, U. S. DEPARTMENT OF AGRICULTURE. 

Specific gravity. — The ratio of the weight of a piece of wood (or 
other substance) , usually oven-dry, to the weight of an equal volume 
of water, with the latter considered as 1. (For most woods the 
specific gravity is less than 1, because they are lighter than water, 
which weighs nearly 62.5 pounds per cubic foot.) 

Storied rays. — Kays arranged in horizontal layers or stories in the 
tree, producing "ripple" marks on tangential faces. (See fig. 12.) 

Summeru'ood.— The outer, often darker and harder portion of 
each annual ring. 

Tangential. — Along a tangent, or at right angles to the radius. 

Tangential surface. — A longitudinal surface cut approximately at 
right angles to the rays, equivalent to flat grain or plain-sawed 
surface. 

Tyloses. — Glistening, froth-like ingrowths in the pores of the 
heartwood, closing them up more or less. 



ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 

THE SUPERINTENDENT OF DOCUMENTS 

GOVERNMENT PRINTING OFFICE 

WASHINGTON, D. C. 

AT 

10 CENTS PER COPY 



A 



V ft \ 8 I"/* 



m 



i * 



« !% I 













Fig. 3. Spanish Cedar. End Grain Magnified 
7.5 Diameters. 









• .-* "j J, 





■ K -r; 


* » 




* 




>MS^JiTM-^Wl 



Fig. 4. — Sapeli. End Grain Magnified 7.5 
Diameters. 







*|'>fi<3^ ;,• -^^i.j^n igti-.-^ --.%' ^'•'•A-> -«iV'^^ 



Fig. 5. — "African Mahogany." End Grain 
Magnified 7.5 Diameters. 




Fig. 6. — "Philippine Mahogany." End Grain 
Magnified 7.5 Diameters. 





• 'S - '> -, 




HP|MJa^- 






|SBH|BiEj 




5 




1 


& 


m^^ 


■ 


^^m 



Fig. 7. — "Colombian Mahogany." End Grain 
Magnified 7.5 Diameters. 







4 »,i', ^ *'.)> *T 









i*>!tll.i 1^ J ! 



I^<:^«iii<liii^l 




Fig. 8. — "LiBERViLLE Mahogany." End Grain 
Magnified 7.5 Diameters. 



i" -'//•.'• •.• •/. ^ = '•'/* «"..* '.••' ' \f ^'■■ 




• •■ • . » • 



•^;;: ''■'. .'xv.'' V;':;^ ■^'::!.^^y';^•':''v^/•.'• 



Fig. 9. — Yellow Birch. End Grain Magnified 
7.5 Diameters. 



pftilSlIlii,3'^' 









i 

I 



ii ir^[: 



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;i 









Fig. 10. — Red Gum. End Grain Magnified 
7.5 Diameters. 




Fig. II. — "White Mahogany." End Grain 
Magnified 7.5 Diameters. 




m 



mm 



^m§ 



1 i ; » 






Fig. 12. — Tangential Surface of True Mahogany 
showing the Rays more or less in Horizontal 
Rows OR Stories. 






tn 





Fig. 



13. — Radial Surface of Crabwood Showing 
Dark Rays. 



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